Lighting apparatus



Oct. 10, 1950 e. R. BAUMGARTNER LIGHTING APPARATUS Filed Dec. 7, 1945 INVENTOR: GEORGE R. BAUM BY HIS GARTN ER ML M ATTORNEY increases as the vertices of the ellipse are approached.

I have demonstrated that a Searchlight comprising a 24 inch parabolic reflector having the spread and of higher candlepower at the higher angles than the beam projected by the same Searchlight except for the use, of an uncoated. cylindrical glass tube in place of the tube I described above. qcy-lindrical tube approximately 14 mm. in diam- Specifically, when an uncoated eter was used the candlepower at the axis of the beam was 10,500 in a horizontal plane in- .cluding the beam axis and at degree on either side of the said axis it averaged 3,300; at degree 900; at 1 degree 400, and atl fl degrees 100. When the coated ellipticaltube I described above was substituted for the cylindrical tube in the lamps 2, and through spring contacts 24 mounted on and electrically connected to the metal plate 2| which may be connected to a suitable terminal of the power source.

Each tube I! has a metal film constituting a reflector 25 alongside of the light emitting portions of the lamps 2 as in the embodiment of the invention shown in Figs. 1 and 2 and each reflector 25 directs the light emitted by the lamp 2 it surrounds in the same manner as the reflector [5 of Figs. 1 and 2. Thus, when the apparatus shown in Figs. 3 and 4 is mounted at the same searchlight and the same measurements made in the same plane and in the same manner the candlepower at the beam axis was 11,000; at

A degree it averaged 4,300;'at degree and 1 .degree 2,350; at 1% degrees 1,650; at 1% degrees 1 1,800, and at 2 degrees 400.. v

The candlepower distribution of the searchlight in a vertical plane with the uncoated cylindrical tube was 10,500 at the beam axis; averaged 9,550 atl degree from the beam axis; 6,200 at 2 degrees, and 450 at 3 degrees.

tive for increasing the spread of the beam and the candlepower at the higher angles of spread of the beam projected by the searchlight.

The apparatus shown in Figs. 3 and 4 of the drawing is similar to that shown in Fig. 1 except that in this embodiment two mercury vapor arc lamps 2 are mounted side by side in a jacket comprising a heavy, cylindrical outer glass tube l6 and each lamp 2 is surrounded by an elliptical glass tube l1 terminating short of one end of the lamp. The major and minor axes of tubes I! are of the same length as those of tube I of Figs. 1 and 2. Cooling water may flow into and out of the jacket through the nipples 18 which are connected to the interior of the glass tubes H by passages in the electrically insulating plate It which is engaged by a metal holder 20. The glass tubes I! are mounted on the plate [9 with the joints watertight and the outer glass tube I6 is recessed into an annular groovein the plate l9 and a similar groove in the metal upper plate 2|. The joints between the ends of the outer tube l6 and the plates l9 and 2| are made watertight by soft rubber gaskets. Retaining bolts 22 engage holder 20 and plate 2| and clamp the assembly together. Electrical connections to the lamp terminals I0 and M of the lamps 2 are made through the stationary contacts 23 in the elliptical tubes I! which contacts 23 extend through the insulator plate I9 for connection to terminals of an electric power source for the icons of a parabolic reflector in a searchlight a single beam of high candlepower is projected rather than distinctpencil beams which was obtained with similar apparatus in which the glass tubes I! were cylindrical and free from a reflecting coating.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A liquid-cooled mount for an elongated high pressure mercury vapor discharge. lamp'having its end terminals exposed to the cooling liquid comprising a light transmitting tube havinga portion elliptical in cross section closely surrounding the light emitting portion of the lamp and a coating of reflecting metal on said tube portion and completely covering one-half of said portion symmetrical with its minor axis.

2. A liquid-cooled mount for an elongated high pressure mercury vapor discharge lamp having comprising a jacket through which cooling liquid "may circulate and at least a portion of which is light transmitting, means to support the lamp within said jacket portion and a light transmitting tube within said jacket having a portion elliptical in cross section closely surrounding the light emitting portion of the lamp and a coating of reflectingmetal on said tube portion and completely covering one-half of said portion symmetrical with its minor axis.

3. A liquid-cooled mount for a plurality of elongated high pressure mercury vapordischarge lamps having its end terminals exposed to the cooling liquid comprising a jacket through which cooling liquid may circulate and at leastaportion ofwhich is light transmitting, means to support the said lamps in parallel juxtaposed positions within said jacket portion, a plurality of light transmitting tubes one for each of said lamps within said jacket each having a portion elliptical in cross section closely surrounding the light emitting portion of its respective lamp and a coating of reflecting metal on .said tube portion and completely covering one-half of said portion symmetrical with its minor axis.

GEORGE R. BAUMGAR'INER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,241,098 Doyle et a1. Sept. 25, 1917 1,359,789 Brown Nov. 23, 1920 2,265,362 Elenbaas Dec. 9, 1941 2,312,232 Bol Feb. 23, 1943 FOREIGN PATENTS Number Country Date 336,779 Great Britain Oct. 23, 1930 474,779 Great Britain Nov. 8, 1937 

